The present invention relates to a heat pump and a dehumidifying apparatus, and more particularly to a heat pump with a high COP and a dehumidifying apparatus which has such a heat pump.
As shown in FIG. 17, there has heretofore been available a desiccant air-conditioning apparatus having a heat pump as a heat source. The air-conditioning apparatus shown in FIG. 17 employs a compression type heat pump HP including a compressor 260 as the heat pump. The air-conditioning apparatus has a path for process air A from which moisture is adsorbed by a desiccant wheel 103, and a path for regeneration air B which is heated by a heating source and then passes through the desiccant wheel 103 which has adsorbed the moisture, to desorb the moisture from the desiccant for thereby regenerating the desiccant. The air-conditioning apparatus has an air-conditioner having a sensible heat exchanger 104 for exchanging heat between the process air from which moisture has been adsorbed and the regeneration air before it regenerates the desiccant of the desiccant wheel 103 and also before it is heated by the heating source, and also has the compression type heat pump HP. The regeneration air of the air-conditioner for regenerating the desiccant is used as a high-temperature heat source in the compression type heat pump HP, and is heated by a heating unit 220. The process air of the air-conditioner is used as a low-temperature heat source in the compression type heat pump HP, and is cooled by a cooling unit 210.
Here, operation of the compression type heat pump HP shown in FIG. 17 will be described below with reference to a Mollier diagram shown in FIG. 18. The diagram shown in FIG. 18 is a Mollier diagram in the case where HFC134a is used as the refrigerant. A point a represents a state of the refrigerant evaporated by the cooling unit 210, and the refrigerant is in the form of a saturated vapor. The refrigerant has a pressure of 4.2 kg/cm2, a temperature of 10xc2x0 C., and an enthalpy of 148.83 kcal/kg. A point b represents a state of the vapor drawn and compressed by the compressor 260, i.e., a state at the outlet port of the compressor 260. In this state, the refrigerant has a pressure of 19.3 kg/cm2 and a temperature of 78xc2x0 C., and is in the form of a superheated vapor. The refrigerant vapor is cooled in the heating unit (as a cooling unit or a condenser from the viewpoint of the refrigerant) 220 and reaches a state represented by a point c in the Mollier diagram. In the point c, the refrigerant is in the form of a saturated vapor and has a pressure of 19.3 kg/cm2 and a temperature of 65xc2x0 C. Under this pressure, the refrigerant is further cooled and condensed to reach a state represented by a point d. In the point d, the refrigerant is in the form of a saturated liquid and has the same pressure and temperature as those in the point c. The saturated liquid has an enthalpy of 122.97 kcal/kg. The refrigerant liquid is depressurized by an expansion valve 250 to a saturation pressure of 4.2 kg/cm2 at a temperature of 10xc2x0 C. The refrigerant is delivered as a mixture of the refrigerant liquid and the vapor at a temperature of 10xc2x0 C. to the cooling unit (as an evaporator from the viewpoint of the refrigerant) 210, where the mixture removes heat from process air and is evaporated to reach a state of the saturated vapor, which is represented by the point a in the Mollier diagram. The saturated vapor is drawn into the compressor 260 again, and the above cycle is repeated.
The heat pump used in the above conventional air-conditioning apparatus does not have an excellent COP because the cooling effect of a refrigerant in a refrigerant cycle is not necessarily large. In the conventional air-conditioning apparatus, the sensible heat exchanger 104 for preliminarily cooling the process air before the process air is cooled by the cooling unit 210 plays an important role. However, since the sensible heat exchanger generally occupies a large volume in the system, it is difficult to construct the system, and the system unavoidably becomes large in size.
It is therefore an object of the present invention to provide a heat pump having a high COP and a dehumidifying apparatus which has a high COP and a compact structure.
According to an aspect of the present invention, as shown in FIGS. 1 and 2, for example, there is provided a heat pump HP 1 in which a pressurizer 260, a condenser 220, and an evaporator 210 are interconnected via refrigerant paths 201-207, the heat pump comprising: means disposed in the refrigerant path interconnecting the condenser 220 and the evaporator 210, for alternately evaporating and condensing a refrigerant repeatedly under an intermediate pressure which is located intermediately between a pressure to be pressurized by the pressurizer 260 and a pressure which has been pressurized by the pressurizer 260 (from a point e to a point f1 and from a point f1 to a point g1a and the like in FIG. 3).
The heat pump may be arranged such that while the refrigerant is alternately being evaporated and condensed repeatedly as shown in a flow diagram shown in FIG. 9 and a corresponding Mollier diagram shown in FIG. 10, for example, the condensed refrigerant is condensed after it is depressurized to a second intermediate pressure lower than the previous intermediate pressure (from a point g2 to a point E in FIG. 10). For example, the heat pump may have two means for alternately evaporating and condensing the refrigerant repeatedly as shown in a flow diagram shown in FIG. 12 and a corresponding Mollier diagram shown in FIG. 13, and the heat pump may be arranged such that the evaporation pressure and the condensation pressure in one of the means is made lower than the evaporation pressure and the condensation pressure in the other means, and while the refrigerants are alternately being evaporated and condensed repeatedly by the respective means, the condensed refrigerants are concurrently depressurized to an evaporation pressure in the evaporator (from a point g2 to a point j1 and from a point G2 to a point j in FIG. 13).
According to an aspect of the present invention, there is provided a dehumidifying air-conditioning apparatus comprising: a moisture adsorbing device 103 for removing moisture from process air and for being regenerated by desorbing moisture therefrom with regeneration air; and a heat pump HP1 having a condenser 220, an evaporator 210, and a thin pipe group interconnecting the condenser 220 and the evaporator 210; wherein the thin pipe group is arranged so as to introduce a refrigerant condensed by the condenser 220 to the evaporator 210 and to bring the refrigerant into alternate contact with the process air and the regeneration air.
As shown in FIG. 12 or FIG. 14, for example, there may be two of the above thin pipe group, the refrigerant path for introducing the refrigerant from the condenser to the thin pipe groups may be branched into two passages which are connected respectively to the two of the thin pipe groups, and refrigerant pipes extending from the respective thin pipe groups may be joined to each other at the inlet of the evaporator or directly in the evaporator.
According to another aspect of the present invention, as shown in FIGS. 1 and 2, for example, there is provided a heat pump comprising: a pressurizer 260 for raising a pressure of a refrigerant; an evaporator 210 for cooling a low-temperature heat source fluid A with heat of evaporation of the refrigerant to be pressurized by the pressurizer 260; a condenser 220 for heating a high-temperature heat source fluid B with heat of condensation of the refrigerant pressurized by the pressurizer 260; and a first heat exchanger 300a for exchanging heat between the low-temperature heat source fluid A upstream of the evaporator 210 and a cooling fluid; wherein the first heat exchanger 300a has a first compartment 310 through which the low-temperature heat source fluid A flows, a second compartment 320 through which the cooling fluid flows, and refrigerant passages 215A1-A9, 252A1-A9 extending through the first compartment 310 and the second compartment 320, the refrigerant passages 215A1-A9, 252A1-A9 being connected to the condenser 220 through a first restriction 330, extending alternately through the first compartment 310 and the second compartment 320 repeatedly, and then being connected to the evaporator 210 through a second restriction 250. The cooling fluid should preferably comprise the high-temperature heat source fluid B. Particularly, the cooling fluid which is to exchange heat with the cold heat source fluid upstream of the evaporator in the first heat exchanger 300a should preferably comprise the high-temperature heat source fluid B upstream of the condenser 220.
In the refrigerant passage, the refrigerant typically flows in one direction as a whole. This means that the refrigerant flows in substantially one direction through the refrigerant passage when views as a whole even though the refrigerant may locally flow back due to turbulences or may be vibrated in the flowing direction due to pressure waves produced by bubbles or instantaneous interruptions. The refrigerant passage comprises a heat exchange tube, for example, and extends alternately through the first compartment and the second compartment. Therefore, the refrigerant which flows in one direction as a whole is alternately evaporated and condensed repeatedly. The expression that the refrigerant passage extends alternately through the first compartment and the second compartment means that the refrigerant passage does not run through the first compartment and the second compartment only once, but the refrigerant passage runs through the first compartment and the second compartment once and then runs at least once through the second compartment or the first compartment. In the first compartment, the low-temperature heat source fluid exchanges heat with the refrigerant, and in the second compartment, the high-temperature heat source fluid exchanges heat with the refrigerant. Typically, the refrigerant is at least partly evaporated in the refrigerant passage which extends through the first compartment, and the refrigerant in the vapor phase is at least partly evaporated in the refrigerant passage which extends through the second compartment.
With the above arrangement, since the refrigerant passes through the first and second compartments a plurality of times, the refrigerant will not completely be dried out even if it is evaporated in the refrigerant passage extending through the first compartment.
In the heat pump, the first compartment 310 and the second compartment 320 may be arranged such that the low-temperature heat source fluid A and the cooling fluid flow as counterflows; the refrigerant passage in the first compartment 310 and the second compartment 320 may have at least a pair of a first compartment extending portions 251A1 and a second compartment extending portions 252A1 in a first plane PA which is substantially perpendicular to the flows of the low-temperature heat source fluid A and the cooling fluid, at least a pair of a first compartment extending portions 251B1 and a second compartment extending portions 252B1 in a second plane PB, different from the first plane PA, which is substantially perpendicular to the flows of the low-temperature heat source fluid A and the cooling fluid, and an intermediate restriction 331 disposed in a transitional location from the first plane PA to the second plane PB.
In the portion of the refrigerant passage which extends through the first compartment, at least a portion of the refrigerant is typically evaporated. That portion of the refrigerant passage may thus be referred to as an evaporating section. In the portion of the refrigerant passage which extends through the second compartment, at least a portion of the refrigerant is typically condensed. That portion of the refrigerant passage may thus be referred to as a condensing section. The pair which is mentioned above refers to a pair of the evaporating section and the condensing section (or the condensing section and the evaporating section). Since the heat pump has the intermediate restriction, the pressure in the refrigerant passage in the first plane and the pressure in the refrigerant passage in the second plane may have different values. Since the low-temperature heat source fluid and the cooling fluid flow as counterflows, the different pressures become progressively lower in the downstream direction of the low-temperature heat source fluid or in the upstream direction of the cooling fluid. Therefore, the low-temperature heat source fluid and the cooling fluid perform counterflow heat exchange therebetween, resulting in an extremely high heat exchange efficiency.
In the above heat pump, the intermediate restriction 331 may be located in a position where the refrigerant passage has extended through the second compartment 320 as shown in FIG. 1, for example, or the intermediate restriction 331 may be located in a position where the refrigerant passage has extended through the first compartment 310 as shown in FIG. 6, for example.
For example, as shown in FIG. 12, the heat pump may further comprise a second heat exchanger 300d2 for exchanging heat between the low-temperature heat source fluid A upstream of the evaporator 210 and the cooling fluid; wherein the second heat exchanger 300d2 has a third compartment 310B through which the low-temperature heat source fluid A flows, a fourth compartment 320B through which the cooling fluid flows, and a refrigerant passage extending through the third compartment 310B and the fourth compartment 320B, the refrigerant passage being connected to the condenser 220 through a third restriction 330B, extending alternately through the third compartment 310B and the fourth compartment 320B repeatedly, and then being connected to the evaporator 210 through a fourth restriction 340B; and the third compartment 310B is disposed downstream of the first compartment 310A with respect to the low-temperature heat source fluid A, and the fourth compartment 320B is disposed upstream of the second compartment 320A with respect to the cooling fluid. The cooling fluid should preferably comprise the high-temperature heat source fluid B. Particularly, the cooling fluid which is to exchange heat with the cold heat source fluid upstream of the evaporator in the second heat exchanger 300d2 should preferably comprise the high-temperature heat source fluid B upstream of the condenser 220.
With the above arrangement, since the heat pump has the second heat exchanger 300d2, the heat pump can operate under a pressure different from the pressure of the first heat exchanger, thus increasing an overall heat exchange efficiency.
For example, as shown in FIG. 9, the heat pump may further comprise a third heat exchanger 300c2 for exchanging heat between the low-temperature heat source fluid A upstream of the evaporator 210 and the cooling fluid; wherein the third heat exchanger 300c2 has a fifth compartment 310B through which the low-temperature heat source fluid A flows, a sixth compartment 320B through which the cooling fluid flows, and a refrigerant passage extending through the fifth compartment 310B and the sixth compartment 320B, the refrigerant passage being connected to the refrigerant passage of the first heat exchanger 300c1 through a fifth restriction 340, extending alternately through the fifth compartment 310B and the sixth compartment 320B repeatedly, and then being connected to the evaporator 210 through the second restriction 250; and the fifth compartment 310B is disposed downstream of the first compartment 310A with respect to the low-temperature heat source fluid A, and the sixth compartment 320B is disposed upstream of the second compartment 320A with respect to the cooling fluid. The cooling fluid should preferably comprise the high-temperature heat source fluid B. Particularly, the cooling fluid which is to exchange heat with the cold heat source fluid upstream of the evaporator in the third heat exchanger 300c2 should preferably comprise the high-temperature heat source fluid B upstream of the condenser 220.
According to still another aspect of the present invention, as shown in FIGS. 1, 6, 9, and 12, for example, there is provided a dehumidifying apparatus comprising: the above heat pump; and a moisture adsorbing device 103 disposed upstream of the first heat exchanger with respect to the low-temperature heat source fluid A and having a desiccant for adsorbing moisture from the low-temperature heat source fluid A.
The low-temperature heat source fluid is typically the process air of the air-conditioning apparatus. Since the air-conditioning apparatus has a moisture adsorbing device, the humidity of the low-temperature heat source fluid can be lowered. The high-temperature heat source fluid is typically outside air as regeneration air.
The present dehumidifying apparatus should preferably be arranged so as to desorb the moisture of the desiccant with the high-temperature heat source fluid B which is heated by the condenser 220.
As shown in FIG. 3, for example, the object of the present invention can also be achieved by a method of transferring heat from a low-temperature heat source fluid A to a high-temperature heat source fluid B, the method comprising: a first step of evaporating a refrigerant by cooling a low-temperature heat source under a predetermined low pressure of 4.2 kg/cm2 (from a point j to a point a); a second step of raising a pressure of the refrigerant which has been evaporated in the first step to a predetermined high pressure of 19.3 kg/cm2 (from the point a to a point b); a third step of condensing the refrigerant pressurized in the second step under the predetermined high pressure to heat a high-temperature heat source fluid with heat of condensation (from the point b to a point d); a fourth step of depressurizing the refrigerant which has been condensed in the third step to a first intermediate pressure between the predetermined high pressure and the predetermined low pressure (from the point d, a point c to a point e); a fifth step of repeatedly evaporating the refrigerant depressurized in the fourth step by cooling the low-temperature heat source fluid and condensing the refrigerant by heating the high-temperature heat source fluid; and a sixth step of providing the refrigerant which has been condensed in the fifth step as the refrigerant to be evaporated in the first step. The transfer of heat is typically performed by the pumping of heat.
As shown in FIG. 3, for example, the repeated evaporation and condensation in the fifth step is achieved by evaporation by cooling the low-temperature heat source fluid A (from the point e to a point f1, from a point h1 to a point f2, from a point h2 to a point f3, from a point h3 to a point h4) and condensation by heating the high-temperature heat source fluid B (from the point f1 to a point g1a, from a point g1b to the point h1, from a point f2 to a point g2a, from a point g2b to the point h2, and the like). In the example shown in FIG. 3, the sixth step is a step (from a point h4 to the point j) of providing, as the refrigerant to be evaporated in the first step, the refrigerant which has been condensed (from the point f4 to the point h4) by heating the high-temperature heat source fluid B.
There may be provided a dehumidifying method comprising the above method of pumping heat, and, as shown in FIG. 4, for example, an eleventh step of adsorbing, with a desiccant, moisture contained in the low-temperature heat source fluid before it is cooled by evaporating the refrigerant in the fifth step (from a point K to a point L); and a twelfth step of desorbing moisture from the desiccant which has adsorbed the moisture in the eleventh step, with the high-temperature heat source fluid which has been heated by condensing the refrigerant in the third step (from a point T to a point U).
The present application is based on Japanese patent application No. 11-245022 filed on Aug. 31, 1999, which is incorporated herein as part of the disclosure of the present application.
The present invention can more fully be understood based on the following detailed description. Further applications of the present invention will become more apparent from the following detailed description. However, the following detailed description and specific examples will be described as preferred embodiments only for the purpose of explaining the present invention. It is evident to a person skilled in the art that various changes and modifications can be made to the embodiments in the following detailed description within the spirit and scope of the present invention.
The applicant has no intention to dedicate any of the embodiments described below to the public, and any of the disclosed modifications and alternatives which may not be included in the scope of the claims constitutes part of the invention under the doctrine of equivalent.